Modelling the barriers to multi-stakeholder collaboration for COVID-19 pandemic response: evidence from Sub-Saharan Africa

The aim of this study is to develop a model describing the interactions and interdependence between the obstacles to effective implementation of a collaborative model of pandemic preparedness and response. A comprehensive review of the relevant literature highlighted 15 key variables. The contextual interactions between these barrier variables were identified based on the opinions of experts with COVID-19 pandemic experience and analysed to determine their driving and dependence powers using interpretive structural modelling. The findings indicate that the lack of guidelines and procedures for coordinated actions, differences in organisational culture (working habits) and funding constraints are the most critical barriers to effective multi-stakeholder collaboration. Managers of collaborative programmes, policymakers and researchers should carefully focus on these hindrances because any improvement in them can significantly affect the overall system

Off-line comprehensive 2-dimensional hydrophilic interaction × reversed phase liquid chromatography analysis of procyanidins

The development of an off-line comprehensive 2-dimensional liquid chromatography (2-D-LC) method for the analysis of procyanidins is reported. In the first dimension, oligomeric procyanidins were separated according to molecular weight by hydrophilic interaction chromatography (HILIC), while reversed phase LC was employed in the second dimension to separate oligomers based on hydrophobicity. Fluorescence, UV and electrospray ionisation mass spectrometry (ESI-MS) were employed for identification purposes. The combination of these orthogonal separation methods is shown to represent a significant improvement compared to 1-dimensional methods for the analysis of complex high molecular weight procyanidin fractions, by simultaneously providing isomeric and molecular weight information. The low correlation (r2 < 0.2100) between the two LC modes afforded a practical peak capacity in excess of 2300 for the optimal off-line method. The applicability of the method is demonstrated for the analysis of phenolic extracts of apple and cocoa. © 2009 Elsevier B.V. All rights reserved.Articl

Kinetic optimisation of the reversed phase liquid chromatographic separation of proanthocyanidins on sub-2μm and superficially porous phases

Phenolic compounds, and proanthocyanidins in particular, are important natural molecules which are of significant importance due to their sensory and biological activities. The analysis of proanthocyanidins in natural products is very challenging due to their complex nature. In this study, the kinetic performance of a range of recently developed C18 columns, including sub-2 μm fully porous and 2.6 μm superficially porous particle-packed columns, was evaluated for improved proanthocyanidin analysis. The kinetic plot method was employed to compare the ultimate performance limits of each column in terms of efficiency and speed for different maximum pressures and temperatures using representative proanthocyanidins comprising a range of molecular weights and functionalities as test analytes. By combining plate height data with relevant parameters such as column permeability and mobile phase viscosity, plots of practically attainable efficiencies as a function of analysis time for specific experimental configurations were obtained and performance limits for all investigated supports could accurately be compared. Both fully- and superficially porous particles provided significant speed and/or efficiency gains compared to conventional 5 μm particle packed columns. Analyte properties, particle size and packing quality as well as analysis temperature were all found to have a significant influence on the performance of the presently investigated chromatographic supports. For smaller compounds, higher optimal linear velocities and better performance in the low-efficiency range were observed, while the lower diffusion coefficients of larger procyanidins resulted in lower optimal linear velocities and better performance in the high-efficiency regime. Faster analyses become possible at higher temperatures due to decreased eluent viscosity and faster mass transfer, which was especially beneficial for larger compounds and resulted in dramatic improvement in efficiency. A possible explanation of the abnormal behaviour of oligomeric procyanidins is presented. Our findings indicate that new column formats, when used under optimal conditions, significantly improve the speed and/or efficiency of reversed phase liquid chromatographic analyses of proanthocyanidins. © 2012 Elsevier B.V

Comprehensive two-dimensional liquid chromatographic analysis of rooibos (Aspalathus linearis) phenolics

ArticleRooibos tea is an unique beverage prepared from unfermented and fermented plant material of the endemic Cape fynbos plant, Aspalathus linearis. The well-known health-promoting benefits of rooibos are partly attributed to its phenolic composition. Detailed investigation of the minor phenolic constituents of rooibos is, however, hampered by the limitations associated with conventional HPLC methods used for its analysis. In this study, the applicability of comprehensive two-dimensional liquid chromatographic methods for the in-depth analysis of rooibos phenolics was investigated. Phenolic compounds were separated according to polarity by hydrophilic interaction chromatography (HILIC) in the first dimension, whilst reversed-phase liquid chromatography (RP-LC) provided separation according to hydrophobicity in the second dimension. Ultraviolet photodiode array and electrospray ionisation mass spectrometry were used to identify phenolic compounds. Comprehensive HILIC × RP-LC demonstrated its applicability for the analysis of a diverse range of phenolic compounds in unfermented and fermented rooibos samples, in which large qualitative differences in the phenolic composition were established. The combination of these orthogonal separations provided a significant improvement in resolution, as exemplified by practical peak capacities in excess of 2000 and 500 for off-line and on-line methods, respectively. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Fast method development of rooibos tea phenolics using a variable column length strategy

The development of a method for the separation of standard compounds of the 15 main phenolics found in rooibos tea is presented. The separation of these compounds in a single HPLC analysis is particularly challenging due to the similarity of rooibos phenolics. As a result, multiple methods are often required to analyze all major phenolics in rooibos tea samples. The method development process is significantly enhanced in this study by using the recently introduced automated column coupler in combination with the variable column length strategy. This strategy consists of performing the initial scouting runs, wherein the best separation conditions are determined, on a short column and subsequently fine-tuning the separation on longer columns to benefit from their higher separation performance. It is demonstrated that the method development process can further be expedited by operating each column length at the maximum pressure, in this case 1000 bar. Although this holds in general, it is even more the case for the presently considered sample, since the selectivity of the sample is more pressure- than temperature-dependent. Applying the optimized method to unfermented and fermented aqueous rooibos tea extracts in combination with Q-TOF mass spectrometry, some 30 phenolic compounds are tentatively identified. © 2011 Elsevier B.V.Articl

Chemical composition and antioxidant activity of extracts from Moroccan fresh fava beans pods (Vicia Faba L.).

Background. In Morocco, fava beans are widely used as a main meal or as an ingredient in various traditional recipes, in the form of fresh ripe seeds or dry seeds. In the past, the tender skin of bean pods was also used in certain specific dishes, thus diversifying the diet. However, the peels of the tender bean pods are currently less or not used and considered waste. In Moroccan, fava bean pods peels, traditionally used in food in the past, are today considered as waste. The valorization of fresh fava bean pods could revitalize the use of the specific dishes and diversify the diet. For this reason, the research aimed to assess the nutritional values and biological compounds of the whole fresh fava bean pods (Vicia faba L.). Objective. Evaluate the content of nutrients, total phenolic, flavonoids and tannin contents and antioxidant activity in different extracts of the tender pods of the fava bean (Vicia faba L.). Material and methods. The proximate composition and minerals were determined using AOAC methods. The total phenolic compounds by the Folin-Ciocalteu reagent, the total flavonoids were analyzed using aluminum chloride colorimetric method, the tannins by method of vanillin in an acidic medium and the antioxidant activity was evaluated by DPPH method. Results. The results show that the fresh fava bean pods have a moisture content of 87.31 ± 0.25%, ash 4.67 ± 1.03, and protein 29.11 ± 3.20 g/100 g. The legume samples also contain potassium (1946.8±4.61), phosphorus (483.8 ± 3.14), and calcium (399.6 ±2.25) mg/100 g of dry matter representing at last 40-50% of the RDI. The content of the different extracts of (Vicia faba L) varied from 49.5 to 594.4 mg GAE/ g for the total phenols, from 0.7 mg to 3.4 mg QE/g for flavonoids, and from 4.9 mg to 73.91 mg TAE/g dry weight for tannins. The evaluation of the antioxidant activity in the various extracts revealed a better activity in the methanolic extract (IC50=491.2 μg/mL) compared to others extracts: the MeOH/water extract (IC50=606.61 μg/mL), DCM/ MeOH extract (IC50 = 642.67 μg/mL) and DCM extract below of 50%. Conclusions. This study shows that fava bean pods, traditionally used in food, are rich in macro and micronutrients and bioactive substances, which demonstrates their potential contribution to human food and nutritional security

Toward Unraveling Grape Tannin Composition: Application of Online Hydrophilic Interaction Chromatography × Reversed-Phase Liquid Chromatography–Time-of-Flight Mass Spectrometry for Grape Seed Analysis

Despite the significant importance of tannins in viticulture and enology, relatively little is known about the detailed chemical composition of these molecules. This is due to challenges associated with the accurate analytical determination of the highly structurally diverse proanthocyanidins which comprise tannins. In this contribution, we address this limitation by demonstrating how online comprehensive two-dimensional liquid chromatography (LC × LC) coupled to high resolution mass spectrometry (HR-MS) can be exploited as a powerful analytical approach for the detailed characterization of grape seed tannins. Hydrophilic interaction chromatography (HILIC) and reversed-phase liquid chromatography (RP-LC) were employed in the two dimensions to provide complementary information in terms of separation according to hydrophilicity and hydrophobicity, respectively. Online coupling of HILIC × RP-LC with fluorescence detection and electrospray ionization MS delivered high resolution analysis in a practical analysis time, while allowing selective detection and facilitating compound identification. Time-of-flight (TOF) MS provided high acquisition rates and sensitivity coupled to accurate mass information, which allowed detection of procyanidins up to a degree of polymerization (DP) of 16 and a degree of galloylation up to 8 in a red grape seed extract. This analytical methodology promises to shed new light on these important grape constituents and potentially on their evolution during wine production